What medication is considered first-line treatment for absence seizures?

Ethosuximide is recognized as the first-line treatment for absence seizures, which are characterized by brief episodes of staring and unresponsiveness. The unique mechanism of action of ethosuximide involves the inhibition of T-type calcium channels in thalamic neurons, which is particularly effective in controlling the abnormal bursts of electrical activity associated with absence seizures.

Other medications used to treat seizures, such as valproate and lamotrigine, are effective for a variety of seizure types, including generalized tonic-clonic seizures and focal seizures, but they are not specifically targeted for absence seizures as ethosuximide is. Phenytoin, on the other hand, is primarily used for tonic-clonic seizures and does not effectively address absence seizures, and it may even exacerbate them.

Thus, given its specific action against the pathological processes underpinning absence seizures and its widespread efficacy, ethosuximide is the preferred first-line treatment option.